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Mapping chromatin accessibility in stable cell lines expressing Drosophila Hox proteins, Hox cofactors Extradenticle and Homothorax, and the pioneer factor Gcm [ATAC-seq]

ABSTRACT: We have used stable cell lines expressing selected Hox proteins, Hox cofactors and the pioneer factor Glial cells missing, singly or in combination, to investigate the effects on chromatin accessibility genome-wide using ATAC-Seq.

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE122557 | GEO | 2019/05/15

REPOSITORIES: GEO

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Project description:Hox protein transcription factors specify segmental diversity along the anterior-posterior body axis in metazoans. Understanding the basis of Hox function has long faced the problem that, while the different members of the Hox family show clear functional specificity in vivo, they all show very similar binding specificity in vitro. Based on in vitro studies, Hox cofactors may increase Hox binding selectivity but a satisfactory understanding of in vivo Hox target selectivity is still lacking. We have carried out a systematic analysis of the in vivo genomic binding profiles of all eight Drosophila Hox proteins using transient transfection in Kc167 cells to examine Hox protein targeting. We find that Hox proteins show considerable binding selectivity in vivo in the absence of the canonical Hox cofactors Extradenticle and Homothorax. Hox binding selectivity is strongly associated with chromatin accessibility; binding sites in less accessible chromatin show the highest selectivity and the different Hox proteins exhibit different propensities to bind less accessible chromatin. High Hox binding selectivity is also associated with high affinity binding regions, leading to a model where Hox proteins derive binding selectivity through an affinity-based competition with nucleosomes. Provision of the Extradenticle/Homothorax cofactors generally leads to an increase in the number of Hox binding regions and promotes the binding to regions in less accessible chromatin, however the provision of these cofactors has little effect on the overall selectivity of Hox targeting. These studies indicate that chromatin accessibility plays a key role in Hox selectivity and we propose that relative chromatin accessibility provides a basis for subtle differences in binding specificity and affinity to generate significantly different sets of genomic targets for different Hox proteins. We suggest that this mechanism may also be relevant to other transcription factor families. This SuperSeries is composed of the SubSeries listed below.

Dataset Information

Mapping chromatin accessibility in stable cell lines expressing Drosophila Hox proteins, Hox cofactors Extradenticle and Homothorax, and the pioneer factor Gcm [ATAC-seq]

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